/* NOTICE
    OpenJaWS - Open Java Weather Station
    
    Copyright (C) 2008 Grant Gardner <grant@lastweekend.com.au>
    
    OpenJaWS is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
    
NOTICE */
package au.com.lastweekend.openjaws.api;

import au.com.lastweekend.openjaws.units.Unit;
import au.com.lastweekend.openjaws.util.StringUtil;

/**
 * Structure for storing a value with the unit it was measured in.
 * @author ggardner
 *
 */
public class UnitValue implements StringUtil.DeepFormatter, Comparable<UnitValue> {

    public static final UnitValue NULL = new UnitValue();
    private Double value;
    private Unit unit;

    protected UnitValue() {
        
    }

    public UnitValue(double value, Unit unit) {

        this.value = value;
        this.unit = unit;
    }

    public UnitValue convertTo(Unit to) {

        return new UnitValue(to.convertFrom(value, unit), to);
    }

    public Double getValue() {

        return value;
    }

    public Unit getUnit() {

        return unit;
    }

    public String toString() {

        return format("%f %s");
    }

    public String format(String formatSpec) {

        return StringUtil.deepFormat(formatSpec, this);
    }

    public Object[] formatArgs() {

        return new Object[]{value, unit};
    }

    public int compareTo(UnitValue o) {
        if (this.unit == null || o.unit == null) {
            throw new NullPointerException("Cannot compare nulls " + this + ".compareTo(" + o + ")");
        }
        
        if (o == this) {
            return 0;
        } else {
            return this.value.compareTo(this.unit.convertFrom(o.value, o.unit));
        }
    }

}
